AifDERSON — ON THE TILESTONES OF FORFARSHIRE. 151 



The space cleared at the Coral Den of Tealing, on the day in ques- 

 tion, was about ten feet square, every patch of which contained fossil 

 markings of some kind or other. The Parka decipiens'^ was the most 

 conspicuous, colouring the whole face of the rock, a perfect Ptery- 

 gotean egg-nest inclosed in its sedgy mass of vegetation. As a proof 

 of the denseness of this ancient spawn-bed, in the restored ova of the 

 creature, suffice it to state, that on a portion of the rock now before 

 me, seven inches by five, I enumerate seventy to eighty distinct 

 impressions of the egg-sac. Some flags, two to three feet square, 

 had the whole surface blackened and reticulated with the eggs and 

 pedicles of the oviparous organs. The impressions are generally 

 rounded, and of all sizes, varying from that of a garden-pea to upwards 

 of an inch in diameter ; some of them, indeed, two inches by an inch 

 and a half in length and breadth. The inclosing sac, in some cases, 

 is entire and opaque, showing no portion of the developed eggs or 

 dots ; in other cases, the vessel appears to be bursting, and part of 

 the ova are visible ; while again, in others, the whole clusters are 

 complete, and in their fullest development for the inspection of the 

 microscopist. 



A locality so affluent in the spawn — if spav/n they really be — could 

 not fail to present evidences of the depositor of these curious organ- 

 isms. Tracings accordingly of the huge crustacean were everywhere 

 abundant. The mandibular feet, or jaw-feet, of the Pterygotus 

 turned up, more or less perfect, on almost every flag. Several of the 

 broad plates that envelope the body were likewise found j as also 

 some good specimens of other parts of the carapace. A large swim- 

 ming-foot was among the trophies of the day. But no entire fish, 

 the eager object of search, rose to the captivating beat of the hammer, 

 although we trawled the identical spot where was bagged the splendid 

 specimen exhibited at the Leeds meeting in September last ; and, 



* The probable relationships of the so-caUed Parka decipiens may be— 



1. (?0 A real frait like a blackberry, as remarked by the first observers. 



2. (?) The fiiiit of the sedges which Dr. Anderson says are so plentiful ; 



3. (??) The spawn of fi'og-like beasts, 



4. The spawn of ne^vt-like creatures, to both of which Dr. Mantell has 



referred. 



5. (?) The spawn of Pterygotus, as it is considered by Page and Salter. 

 For information on these points see Dr. Mantell's paper in the Quart. Joum. 



Geolog. Soc, vol.iviii. p. 106, Lyell's "Manual of Geology," Murchison's "Siluria," 

 Page's " Advanced Text-book of Geology," and " The Wonders of Geology" (Mr. 

 Rupert Jones' edition).— Ed. Geol. 



